1. FIELD OF THE INVENTION
This invention pertains to a beverage dispenser having an improved level control for controlling the level of a liquid heat exchange medium within a cooling tank of the dispenser.
2. THE PRIOR ART
Beverage dispensers with ice bath cooling tanks have been popular for many years. A typical ice bath cooling tank includes a tank which is filled with water, a refrigeration evaporator to freeze an ice bank in the water within the tank, serpentine cooling coils through which beverage ingredients such as water and syrup are propelled, an agitator for circulating the water heat exchange medium between the coils, and some type of device for establishing the level of water and ice within the tank; provisions are also usually made for some device to drain the tank of its water.
There are several problems inherent with liquid medium heat exchange. The water level must be maintained. If the level becomes too low, the agitator motors cavitate and gurgle, the quantity of ice will be lessened, and cooling efficiency is reduced. If the water level becomes too high, water will creep into the agitator motor and effect bearing seizure or burn out, water will be thrown out of the tank, and the entire dispenser will become wet. The natural tendency of these dispensers is for the quantity of water within the refrigerated tank to increase because of condensation of humidity from ambient air. Contamination of bath water is also a problem. Over a period of time, organic growths tend to appear in the tank much like that grown on a river bottom. There are two ways to combat this, either toxic chemical additives or periodic changes of the bath water.
One of the prior structures used to control bath water level is a notch in the upper wall of the tank. Excess water merely runs over the side. The disadvantages are the water runs into the components of the dispenser, the water tends to get into insulation around the tank, it's a mess, corrosion of components adjacent to the notch and disposal of the water run-off. This level control structure also requires a discrete drain structure.
A stand pipe within the tank is another prior structure. There are two types of stand pipe; one is welded in place permanently in the tank and the second structure has a removable pipe.
The welded-in pipe usually projects through the bottom, has a drain hose attached to its bottom and the top of the pipe is at the desired water level. Problems with this structure include freeze-ups, the pipe interferes with circulation of water, the pipe is fragile and easily damaged as refrigeration and/or product cooling coils are removed or installed, it's difficult to manufacture and treat for corrosion resistance, a discrete drain device is required and ambient air tends to draft upwardly in the pipe and effect increased condensation in the tank. This pipe usually needs to be connected into a drain line or else the overflow is run into a base pan and evaporated to atmosphere.
The removable pipe structure has a coupling fitting welded into the tank bottom with the stand pipe having a threaded bottom and wrenchable top. The pipe is removed for draining the tank. The problems are essentially the same as for the welded pipe. In addition, the threads tend to freeze and the pipe twists or breaks during removal, the pipe may not be tightened and leak through the coupling, and the coupling will break out of the tank.
Discrete drain structures used include a petcock valve or a piece of tubing leading out of the bottom tank. The tubing piece usually has a removable plug in its loose end and lies inside and on the bottom of the dispenser.
The foregoing prior art does operate, but is inconvenient and difficult to use. Dispenser owners do not change bath water often enough. Filling of the dispensers is usually done with premeasured volumetric quantities, e.g. 7.5 liters or some such measurement, and contamination, corrosion and loss of heat transfer capability are persistent problems.